This is a weird one and let me preface this by saying that it is probably due to something that I don't understand in Dividend transactions. I hope one of you can help me figure it out.
I have about two dozen "Asset" accounts, e.g. checking, savings, investment, loans, etc. One of these accounts is a checking account in N. Ireland that has just a few deposits and some debit card transactions. Nothing else. Let's call that AIB.
And I have 7 "Liability" accounts, i.e., credit cards.
In order to tell Uncle Sam how much dividend income I had in 2021, I go to Reports > Taxes > Tax Transactions by Category. The list includes many dozens of dividends that I have received in both my "cash" investment account as well as in my 3 IRA accounts. OF course, I need to edit this to eliminate the IRA tax-free accounts.
First weirdness: In the list any dividend in the "cash" account is correctly labelled with that account name (e.g. TDAmeritrade Joint). Any dividend paid in the IRA accounts has the name of the paying stock as the "account". (Yes, Zebulon, I remember what you said about each stock being an "account".) Why aren't they all labelled with either the stock name or the investment account ?
Second, and here is the weirdest one, if I try to configure the report to eliminate an investment account, ALL of the non-TDAmeritrade entries go away. EVEN if I eliminate ONLY the AIB checking account (Remember there are no stocks or dividends in this almost-empty acct.), the report still yields only the dozen or so in the TDAmeritrade joint account. Even if I eliminate ONLY one credit card account, the report shows only the dozen or so from TDA-joint. I am stymied. Thanks as usual for any and all thoughts. A

P.S. This is version 5.1.2 from the repository. (not from an appimage)
I am running plain Ubuntu version 21.10 (impish)
Here is the output of the cmd line:
WebConnect: Try to connect to WebConnect server
WebConnect: Connect to server failed
WebConnect: Running in server mode
System icon theme as reported by QT: "Yaru"
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/onlinejoboutboxview.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/qifexporter.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/konlinetasks_sepa.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/kcm_checkprinting.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/csvexporter.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/checkprinting.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/csvimporter.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/sqlstorage.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/reconciliationreport.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/kcm_forecastview.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/reportsview.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/kcm_qif.so" Validity false
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/kcm_reportsview.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/budgetview.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/kcm_xmlstorage.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/ofximporter.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/qifimporter.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/kbanking.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/xmlstorage.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/kcm_icalendarexporter.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/gncimporter.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/kcm_csvimporter.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/icalendarexporter.so" Validity true
Located plugin "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/forecastview.so" Validity true
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/budgetview.so"
Plugins: budgetview loaded
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/checkprinting.so"
Plugins: checkprinting loaded
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/csvexporter.so"
Plugins: csvexporter loaded
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/csvimporter.so"
Plugins: csvimporter loaded
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/forecastview.so"
Plugins: forecastview loaded
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/gncimporter.so"
Plugins: gncimporter loaded
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/icalendarexporter.so"
Plugins: icalendarexporter loaded
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/kbanking.so"
"Plugins: kbanking loaded, build with (5.6.0stable-0/6.2.10.0stable), run with (5.6.0.0/6.2.10.0)"
3:2021/12/03 17-32-29:(null)(11367):banking_update.c: 610: No AqBanking config folder found at [/home/john-patrick/.aqbanking/settings6/users] (-1)
3:2021/12/03 17-32-29:(null)(11367):banking_update.c: 610: No AqBanking config folder found at [/home/john-patrick/.aqbanking/settings/users] (-1)
3:2021/12/03 17-32-29:(null)(11367):banking_update.c: 411: There is no old settings folder, need initial setup
7:2021-12-03 17:32:29:aqbanking started
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/ofximporter.so"
Plugins: ofximporter loaded
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/onlinejoboutboxview.so"
Plugins: onlinejoboutboxview loaded
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/qifexporter.so"
Plugins: qifexporter loaded
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/qifimporter.so"
Plugins: qifimporter loaded
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/reconciliationreport.so"
Plugins: reconciliation report loaded
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/reportsview.so"
Plugins: reportsview loaded
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/sqlstorage.so"
Plugins: sqlstorage loaded
Loading "/usr/lib/x86_64-linux-gnu/qt5/plugins/kmymoney/xmlstorage.so"
Plugins: xmlstorage loaded
reading file
start parsing file
startDocument
reading securities
endDocument
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
Cost center model created with items 0
Payees model created with items 0
3:2021-12-03 17:32:33:aqbanking banking_compat.c: 58: No account id for alias "42c7d6e7-5379-444e-9285-6073b6922aef-A001266"
3:2021-12-03 17:32:33:aqbanking banking_compat.c: 58: No account id for alias "A001266"
3:2021-12-03 17:32:33:aqbanking banking_compat.c: 58: No account id for alias "42c7d6e7-5379-444e-9285-6073b6922aef-A001266"
3:2021-12-03 17:32:33:aqbanking banking_compat.c: 58: No account id for alias "A001266"
3:2021-12-03 17:32:33:aqbanking banking_compat.c: 58: No account id for alias "42c7d6e7-5379-444e-9285-6073b6922aef-A001266"
3:2021-12-03 17:32:33:aqbanking banking_compat.c: 58: No account id for alias "A001266"
3:2021-12-03 17:32:33:aqbanking banking_compat.c: 58: No account id for alias "42c7d6e7-5379-444e-9285-6073b6922aef-A001266"
3:2021-12-03 17:32:33:aqbanking banking_compat.c: 58: No account id for alias "A001266"
3:2021-12-03 17:35:55:aqbanking banking_compat.c: 58: No account id for alias "42c7d6e7-5379-444e-9285-6073b6922aef-A001266"
3:2021-12-03 17:35:55:aqbanking banking_compat.c: 58: No account id for alias "A001266"
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::begin: Paint device returned engine == 0, type: 2
3:2021-12-03 17:36:35:aqbanking banking_compat.c: 58: No account id for alias "42c7d6e7-5379-444e-9285-6073b6922aef-A001266"
3:2021-12-03 17:36:35:aqbanking banking_compat.c: 58: No account id for alias "A001266"
Plugins: budgetview unloaded
Plugins: checkprinting unloaded
Plugins: csvexporter unloaded
Plugins: csvimporter unloaded
Plugins: forecastview unloaded
Plugins: gncimporter unloaded
Plugins: icalendarexporter unloaded
7:2021-12-03 17:36:35:aqbanking stopped
Plugins: kbanking unplugged
Plugins: kbanking unloaded
Plugins: ofximporter unloaded
Plugins: onlinejoboutboxview unloaded
Plugins: qifexporter unloaded
Plugins: qifimporter unloaded
Plugins: reconciliation report unloaded
Plugins: reportsview unloaded
Plugins: sqlstorage unloaded
Plugins: xmlstorage unloaded

Not a full answer, but notes addressing some of your issues.

- To separate tax deferred income (IRAs and such) I actually have separate categories for each relevant type of income, such as interest, dividends, short and long term capital gains. This makes it easier to transfer the numbers from a tax report to whatever tax software I use.

- Your first weirdness talks about dividends in a cash account. I don't know if it would make any difference, but if you are talking about the brokerage account for the investment account, it is generally advised to use a checking account.

- For your second weirdness, I thought it sounded familiar - see https://bugs.kde.org/show_bug.cgi?id=427541. So, it's been documented, but not yet solved. My short-term suggestion is just to not filter out anything in the report, and just selectively transfer data from the report to your tax software.

As a side note, I have thought about finding away to save report data as a csv in a way you can easily do further filtering in a spreadsheet, but I have not identified any reasonable way to approach that yet.

Thank you, sir. I read through the bug report and I don't feel so alone anymore.
A

OK, I have fixed the weirdest problem above, but I am not sure how exactly.
My dividends are entered manually and sometimes by importing from my investment firm. I found that some are entered directly in the associated brokerage account and some in the investment account. In that latter case, there is an automatically-created entry in the brokerage account that has the Category of "(split) Investment Transaction". When you expand that split it has the entries of (1) Dividend: $100 and (2) Stock name: $0.
So, I spent a good bit of time today manually editing all of those Brokerage entries. I would clear the split and make it a simple dividend entry (Clear Zero and OK). This also removed it from the Investment account. After doing all of those, the reporting is stable. I can omit any and all accounts from a report and the behavior is as expected.
I will be happy to try any tests that might help uncover why or how the original problem is connected to this "solution". Thanks for reading.
A

It will take some thought about whether that approach is really good or not. One problem with removing the $0 split to the investment account is that while you do retain a deposit to the brokerage account in the appropriate category, you will lose the information that that particular dividend came from that particular stock. For tax reporting, it may not matter, but in terms of return on investment for that stock, you have lost some information.

After doing a couple and checking the reports, I noticed that the security link was lost. So, I reestablished the link by entering the name of the stock in the first line "From", still only in the Brokerage account. This works. Thanks,
A